Sometimes Zane will go on yowling jags for no apparent reason. He'll stand in front of his full water dish/food bowl and yowl. When I hear it I think, 'Perhaps he needs more water,' but I go there and see that the dish is full. Sometimes he does it as he wanders through the house; I thought he was missing my late father, whose cat he was, but father's been gone for almost two years now. When he gets in these moods he doesn't want to be petted and will snap at me if I try. It is especially disturbing in the middle of the night when I'm awakened from a sound sleep by it. When he does that he sounds like he's sick or hurt, but I turn on the lights and find him and there's nothing wrong with him. The vet's examined him to a fare-thee-well, and there's nothing organically wrong with him.